Question 1

Which of the following responses correctly lists the order of events in a generalized viral replicative cycle?

Accepted Answer

A)  enzymes transcribe the viral genome into mRNA, the virus enters the cell, host enzymes replicate the viral genome 
B)  the virus enters the cell, host enzymes replicate the viral genome, enzymes transcribe the viral genome into mRNA 
C)  host enzymes replicate the viral genome, enzymes transcribe the viral genome into mRNA, the virus enters the cell 
D)  the virus enters the cell, enzymes transcribe the viral genome into mRNA, host enzymes replicate the viral genome 
A)  enzymes transcribe the viral genome into mRNA, the virus enters the cell, host enzymes replicate the viral genome 
B)  the virus enters the cell, host enzymes replicate the viral genome, enzymes transcribe the viral genome into mRNA 
C)  host enzymes replicate the viral genome, enzymes transcribe the viral genome into mRNA, the virus enters the cell 
D)  the virus enters the cell, enzymes transcribe the viral genome into mRNA, host enzymes replicate the viral genome B

Question 2

Please use the following information to answer the question(s) below.
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA. Table 17.1 shows the results of testing five viruses (A-E) for nuclease sensitivity , the ability of the viral genome to act as an mRNA, and the presence (+) or absence (-) of each virus's own polymerase.   Table 17.1
-Some viruses can be crystallized and their structures analyzed. One such virus is yellow mottle virus, which infects beans. This virus has a single-stranded RNA genome containing about 6,300 nucleotides. Its capsid is 25-30 nm in diameter and contains 180 identical capsomeres. If the yellow mottle virus capsid has 20 facets, how many proteins form each facet?

Accepted Answer

A)  1 
B)  5 
C)  9 
D)  20 
E)  180 
A)  1 
B)  5 
C)  9 
D)  20 
E)  180 C

Question 3

Figure 17.1
-Which of the three types of viruses shown in Figure 17.1 would you expect to include a capsid(s) as part of their overall structure?

Accepted Answer

A)  I only 
B)  II only 
C)  III only 
D)  all three 
A)  I only 
B)  II only 
C)  III only 
D)  all three D

Question 4

Please use the following information to answer the question(s) below.
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA. Table 17.1 shows the results of testing five viruses (A-E) for nuclease sensitivity , the ability of the viral genome to act as an mRNA, and the presence (+) or absence (-) of each virus's own polymerase.   Table 17.1
-Based on Table 17.1, which virus meets the requirements for a bacteriophage?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 5

Which of the following processes can be effective in preventing the onset of viral infection in humans?

Accepted Answer

A)  taking vitamins 
B)  getting vaccinated 
C)  taking antibiotics 
D)  applying antiseptics 
A)  taking vitamins 
B)  getting vaccinated 
C)  taking antibiotics 
D)  applying antiseptics

Question 6

Refer to the treatments listed below to answer the following question(s).
You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent.
I. Treat the substance with nucleases that destroy all nucleic acids and then determine whether it is still infectious.
II. Filter the substance to remove all elements smaller than what can be easily seen under a light microscope.
III. Culture the substance by itself on nutritive medium, away from any plant cells.
IV. Treat the sample with proteases that digest all proteins and then determine whether it is still infectious.
-If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
E)  either II or IV 
A)  I 
B)  II 
C)  III 
D)  IV 
E)  either II or IV

Question 7

Which of the following is why someone who has had a herpesvirus-mediated cold sore or genital sore may have flare-ups for the rest of his or her life?

Accepted Answer

A)  re-infection by a closely related herpesvirus of a different strain 
B)  re-infection by the same herpesvirus strain 
C)  co-infection with an unrelated virus that causes the same symptoms 
D)  copies of the herpesvirus genome remaining as mini-chromosomes in some host cell nuclei 
A)  re-infection by a closely related herpesvirus of a different strain 
B)  re-infection by the same herpesvirus strain 
C)  co-infection with an unrelated virus that causes the same symptoms 
D)  copies of the herpesvirus genome remaining as mini-chromosomes in some host cell nuclei

Question 8

Which of the following statements correctly describes one difference between vertical and horizontal transmission of plant viruses?

Accepted Answer

A)  Vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant. 
B)  Vertical transmission is the spread of viruses from the upper leaves to the lower leaves of the plant, and horizontal transmission is the spread of a virus among leaves at the same general level. 
C)  Vertical transmission is the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread of viruses among plants of similar size. 
D)  Vertical transmission is the transfer of DNA from one type of plant virus to another, and horizontal transmission is the exchange of DNA between two plant viruses of the same type. 
A)  Vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant. 
B)  Vertical transmission is the spread of viruses from the upper leaves to the lower leaves of the plant, and horizontal transmission is the spread of a virus among leaves at the same general level. 
C)  Vertical transmission is the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread of viruses among plants of similar size. 
D)  Vertical transmission is the transfer of DNA from one type of plant virus to another, and horizontal transmission is the exchange of DNA between two plant viruses of the same type.

Question 9

Figure 17.2
-In Figure 17.2, when new viruses are being assembled (IV), what mediates the assembly?

Accepted Answer

A)  host cell chaperones 
B)  assembly proteins coded for by the host nucleus 
C)  assembly proteins coded for by the viral genes 
D)  nothing; the proteins self-assemble 
A)  host cell chaperones 
B)  assembly proteins coded for by the host nucleus 
C)  assembly proteins coded for by the viral genes 
D)  nothing; the proteins self-assemble

Question 10

Which of the following series of events best reflects what we know about how the flu virus moves between species?

Accepted Answer

A)  An avian flu virus undergoes several mutations and rearrangements such that it is able to be transmitted to other birds and then to humans. 
B)  The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected. 
C)  A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans. 
D)  An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, and the virus mutates and can be transmitted to humans. 
A)  An avian flu virus undergoes several mutations and rearrangements such that it is able to be transmitted to other birds and then to humans. 
B)  The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected. 
C)  A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans. 
D)  An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, and the virus mutates and can be transmitted to humans.

Question 11

Please use the following information to answer the question(s) below.
The herpesviruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV), causing chicken pox and shingles. Each of these three actively infects nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others.
-In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell-surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty." Which of the following statements best describes these observations?

Accepted Answer

A)  Viral capsids are needed for the cell to become infected; only the capsids enter the nucleus. 
B)  The viral envelope is not required for infectivity, since the envelope does not enter the nucleus. 
C)  Only the genetic material of the virus is involved in the cell's infectivity, and it is injected like the genome of a phage. 
D)  The viral envelope mediates entry into the cell, the capsid enters into the nuclear membrane, and the genome is all that enters the nucleus. 
E)  The viral capsid mediates entry into the cell, and only the genomic DNA enters the nucleus, where it may or may not replicate. 
A)  Viral capsids are needed for the cell to become infected; only the capsids enter the nucleus. 
B)  The viral envelope is not required for infectivity, since the envelope does not enter the nucleus. 
C)  Only the genetic material of the virus is involved in the cell's infectivity, and it is injected like the genome of a phage. 
D)  The viral envelope mediates entry into the cell, the capsid enters into the nuclear membrane, and the genome is all that enters the nucleus. 
E)  The viral capsid mediates entry into the cell, and only the genomic DNA enters the nucleus, where it may or may not replicate.

Question 12

Most molecular biologists think that viruses originated from naked bits of cellular nucleic acid. Which of the following observations supports this theory?

Accepted Answer

A)  Viruses contain either DNA or RNA. 
B)  Viruses are enclosed in protein capsids rather than plasma membranes. 
C)  Viruses can reproduce only inside host cells. 
D)  Viruses can infect both prokaryotic and eukaryotic cells. 
E)  Viral genomes are usually similar to the genome of the host cell. 
A)  Viruses contain either DNA or RNA. 
B)  Viruses are enclosed in protein capsids rather than plasma membranes. 
C)  Viruses can reproduce only inside host cells. 
D)  Viruses can infect both prokaryotic and eukaryotic cells. 
E)  Viral genomes are usually similar to the genome of the host cell.

Question 13

Which viruses have single-stranded RNA that acts as a template for DNA synthesis?

Accepted Answer

A)  lytic phages 
B)  proviruses 
C)  viroids 
D)  bacteriophages 
E)  retroviruses 
A)  lytic phages 
B)  proviruses 
C)  viroids 
D)  bacteriophages 
E)  retroviruses

Question 14

Which of the following statements correctly describes one characteristic of the lytic cycle of viral replication?

Accepted Answer

A)  Many bacterial cells containing viral DNA are produced. 
B)  Viral DNA is incorporated into the host genome. 
C)  The viral genome replicates without destroying the host. 
D)  A large number of phages are released at a time. 
A)  Many bacterial cells containing viral DNA are produced. 
B)  Viral DNA is incorporated into the host genome. 
C)  The viral genome replicates without destroying the host. 
D)  A large number of phages are released at a time.

Question 15

Figure 17.1
-Which of the three types of viruses shown in Figure 17.1 would you expect to include glycoproteins as part of their overall structure?

Accepted Answer

A)  I only 
B)  II only 
C)  III only 
D)  I and II only 
A)  I only 
B)  II only 
C)  III only 
D)  I and II only

Question 16

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

Accepted Answer

A)  The plants would develop some but not all of the symptoms of the TMV infection. 
B)  The plants would develop symptoms typically produced by viroids. 
C)  The plants would develop the typical symptoms of TMV infection. 
D)  The plants would not show any disease symptoms. 
A)  The plants would develop some but not all of the symptoms of the TMV infection. 
B)  The plants would develop symptoms typically produced by viroids. 
C)  The plants would develop the typical symptoms of TMV infection. 
D)  The plants would not show any disease symptoms.

Question 17

Please use the following information to answer the question(s) below.
The herpesviruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV), causing chicken pox and shingles. Each of these three actively infects nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others.
-In order to be able to remain latent in an infected live cell, HSV must be able to shut down what process?

Accepted Answer

A)  DNA replication 
B)  transcription of viral genes 
C)  apoptosis of a virally infected cell 
D)  all immune responses 
A)  DNA replication 
B)  transcription of viral genes 
C)  apoptosis of a virally infected cell 
D)  all immune responses

Question 18

Which of the following statements correctly describes the best predictor of how much damage a virus causes?

Accepted Answer

A)  ability of the infected cell to undergo normal cell division 
B)  ability of the infected cell to carry on translation 
C)  whether the infected cell produces viral protein 
D)  whether the viral mRNA can be transcribed 
A)  ability of the infected cell to undergo normal cell division 
B)  ability of the infected cell to carry on translation 
C)  whether the infected cell produces viral protein 
D)  whether the viral mRNA can be transcribed

Question 19

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

Accepted Answer

A)  T2 protein and T4 DNA. 
B)  T4 protein and T2 DNA. 
C)  T2 protein and T2 DNA. 
D)  T4 protein and T4 DNA. 
A)  T2 protein and T4 DNA. 
B)  T4 protein and T2 DNA. 
C)  T2 protein and T2 DNA. 
D)  T4 protein and T4 DNA.

Question 20

Antiviral drugs that have become useful are usually associated with which of the following properties?

Accepted Answer

A)  ability to remove all viruses from the infected host 
B)  interference with viral replication 
C)  removal of viral proteins 
D)  removal of viral mRNAs 
A)  ability to remove all viruses from the infected host 
B)  interference with viral replication 
C)  removal of viral proteins 
D)  removal of viral mRNAs

Exam 17: Viruses

Which of the following responses correctly lists the order of events in a generalized viral replicative cycle?

Figure 17.1 -Which of the three types of viruses shown in Figure 17.1 would you expect to include a capsid(s) as part of their overall structure?

Which of the following processes can be effective in preventing the onset of viral infection in humans?

Which of the following is why someone who has had a herpesvirus-mediated cold sore or genital sore may have flare-ups for the rest of his or her life?

Which of the following statements correctly describes one difference between vertical and horizontal transmission of plant viruses?

Figure 17.2 -In Figure 17.2, when new viruses are being assembled (IV), what mediates the assembly?

Which of the following series of events best reflects what we know about how the flu virus moves between species?

Most molecular biologists think that viruses originated from naked bits of cellular nucleic acid. Which of the following observations supports this theory?

Which viruses have single-stranded RNA that acts as a template for DNA synthesis?

Which of the following statements correctly describes one characteristic of the lytic cycle of viral replication?

Figure 17.1 -Which of the three types of viruses shown in Figure 17.1 would you expect to include glycoproteins as part of their overall structure?

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

Which of the following statements correctly describes the best predictor of how much damage a virus causes?

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

Antiviral drugs that have become useful are usually associated with which of the following properties?

Introduction: Evolution and the Foundations of Biology

The Chemical Context of Life

Carbon and the Molecular Diversity of Life

A Tour of the Cell

Membrane Transport and Cell Signaling

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Development, Stem Cells, and Cancer

Genomes and Their Evolution

Descent With Modification

Phylogeny

The Evolution of Populations

The Origin of Species

Broad Patterns of Evolution

Early Life and the Diversification of Prokaryotes

The Origin and Diversification of Eukaryotes

The Colonization of Land by Plants and Fungi

The Rise of Animal Diversity

Plant Structure and Growth

Resource Acquisition, Nutrition, and Transport in Vascular Plants

Reproduction and Domestication of Flowering Plants

Plant Responses to Internal and External Signals

Homeostasis and Endocrine Signaling

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Reproduction and Development

Neurons, Synapses, and Signaling

Nervous and Sensory Systems

Motor Mechanisms and Behavior

Population Ecology and the Distribution of Organisms

Species Interactions

Ecosystems and Energy

Global Ecology and Conservation Biology

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